This invention relates to 6-high cold rolling mills having side supported work rolls of the kind described generally in U.S. Pat. No. 4,270,377 and 4,531,394. The improvements described herein are of particular use when the rolling mill is part of a continuous line as described generally in U.S. Pat. No. 5,197,179.
The intermediate and work roll area of a 6-high mill according to the prior art is shown in FIG. 1 and FIG. 2. Salient features of the design are:
1. An adjustment mechanism 11 provides axial shifting of each intermediate roll 13 by means of hydraulic cylinders and a thrust bearing assembly (not shown). The mechanism is mounted on the operator side intermediate roll chocks 12. This mechanism requires two hydraulic connections 18, and an electrical connection 19 for a transducer measuring the axial position of the roll. PA1 2. Lubricating oil or oil mist connections 14 to the intermediate roll chocks are present to provide lubrication to the intermediate roll neck bearings. PA1 3. Side support cluster arm assemblies 15 are each pivotally mounted on a pivot rod (not shown), which spans between the operator side and the drive side intermediate roll chocks 12 and 16 respectively. The terms "operator side" and "drive side" are well known terms of art and refer to the front side of the mill at which the operator is located and to the rear side from which the mill is driven, respectively. These cluster arm assemblies each include a side support roll (not shown) and two sets of side support bearings (not shown), and thus require a lubricating oil or oil mist supply, which is usually achieved using a connection to the pivot rod 17, which is hollow and so can provide a path to the side support bearings through which the lubricating oil can be delivered through hoses 20. PA1 4. Hydraulic cylinders 21, which are mounted between upper and lower intermediate roll chocks 12 and 16, are used to supply balance, bending and counterbending forces to the intermediate rolls. These hydraulic cylinders require hydraulic oil connections to their ports 22, usually four on the drive side and four on the operator side. PA1 5. Two upper work roll lift assemblies (one of which is shown at 23 in FIG. 2), each consist of a hydraulic cylinder (not shown) connected to a pivoting support arm used to support the upper work roll when the mill screwdown is opened, to create a gap between upper and lower work rolls for threading the mill. These assemblies are mounted on the upper intermediate roll chocks at the drive and operator sides, and require two hydraulic connections 24 to each of these upper chocks. PA1 6. Keeper plates (one of which is shown at 25 in FIG. 1) which can be hydraulically or manually actuated and are mounted on the Mae West blocks (shown at 27) attached at the operator side of mill housing 28. These keeper plates engage with slots 26 in the operator side intermediate roll chocks 12 (or in the housing of the lateral adjustment mechanism 11 which is mounted on these chocks) in order to locate each intermediate roll assembly in its correct axial position in the mill and to support any axial thrust which might develop on the roll assemblies during rolling. PA1 1. Apart from feature No. 6 above, they all require hydraulic or lubricating oil connections to the intermediate roll assemblies. Whenever the intermediate rolls are changed, it's necessary to disconnect the pipes, hoses or cables from the assemblies to be removed, and to reconnect the same pipes, hoses or cables to the new intermediate roll assemblies. This takes a fair amount of time, of the order of 15-30 minutes. For cases where intermediate roll changes are infrequent (say fewer than one change per week) the amount of lost time is negligible, but if changes are frequent the amount of lost time is considerable. PA1 2. Mounting the axial adjustment mechanism on the operator side intermediate roll chocks (feature 1) means that for every such chock an adjustment mechanism must be supplied. For mills having only two (or perhaps three) sets of chocks this is not a significant disadvantage, because the ability to do maintenance on these mechanisms when the intermediate roll assemblies are out of the mill means that reliable operation can be maintained without additional spares. However, for very high production mills where several intermediate roll assemblies are required, this becomes very expensive, and it would then be an advantage to be able to mount the axial adjustment mechanisms in a fixed position, so that they could be disengaged from the intermediate roll chocks at roll change time. PA1 3. A similar situation applies for the case of the intermediate roll balance/bending/counterbending cylinders (feature 4) and for the case of the upper work roll lift assemblies (feature 5). It would be advantageous to remove these items from the intermediate roll assemblies and mount them in fixed positions in the mill so that they can be disengaged from the intermediate roll chocks at roll change time. PA1 4. In the case of a mill according to U.S. Pat. No. 5,197,179, where it may be necessary to change intermediate rolls with strip in the mill or passing through the mill, the chock mounted balance/bending/counterbending cylinders of feature 4 cannot be used anyway, because the presence of strip in the mill would prevent removal or insertion of the intermediate roll assemblies if such cylinders were installed. PA1 1. Intermediate roll balance/bending, and counterbalance hydraulic cylinders are incorporated in the "Mae West" blocks and so remain in the mill at roll change time. There is no need to make any hydraulic connections/disconnections at this time. PA1 2. These cylinders are provided with a long stroke, enabling a large separation of upper and lower intermediate and work rolls when work and/or intermediate rolls are changed. This solves four problems and also enables large clearances between work rolls and strip at roll change time, avoiding possibility of marking of rolls or strip if the rolls touch the strip during roll change. The four problems solved are: PA1 a. It is not necessary to use moveable keeper plates, since the large vertical movement of upper and lower intermediate roll chocks causes them to disengage from the keeper plates, which can now be fixed. PA1 b. In a similar manner, intermediate roll axial shift fingers, attached to cylinders which are mounted on both sides of each intermediate roll drive spindle, (if intermediate rolls are driven), each engage with a thrust housing associated with one of the intermediate rolls to be changed. It's not necessary to use any other disconnection mechanism--the large vertical movement of the intermediate rolls is enough to disconnect the axial shift fingers from their respective thrust housing. Hydraulic connections to shift cylinders do not have to be touched. PA1 c. The resulting large gap between work rolls enables the upper work roll support cylinders to be mounted in fixed position on the Mae West blocks, rather than on the upper intermediate roll chocks. These cylinders can thus be permanently piped and there is no need to connect/disconnect them at roll change time. PA1 d. Spring loaded lubricating oil (or oil mist) connections are mounted on the work roll thrust doors, these connections including spring loaded hollow plungers that operate in the vertical direction, and bear against the inner faces of the intermediate roll chocks. The large vertical separation of the intermediate roll chocks at roll change time causes the intermediate roll chocks to come out of contact with these plungers, enabling the rolls to be removed. It is not necessary to provide any other device to connect and disconnect lubricating oil supply to the chocks and cluster arms at roll change time. The vertical movement of the chocks is sufficient.
These features all provide important functions, and for many applications the features described do a very good job and represent a very cost effective approach. However, singly, or as a group, they suffer from disadvantages under some conditions.
It is the object of this invention to provide an arrangement whereby no hydraulic cylinders are mounted on the intermediate roll chock assemblies, and to provide improved methods of connecting and disconnecting the lubricating oil supply to these chocks during roll change, that will not require manual intervention.
The invention provides the following features which enable the problems of the prior art rolling mills to be overcome.
The fundamental problem of mounting intermediate roll axial shift cylinders at the sides of the drive spindles is that these cylinders occupy the space needed by the spindle clamps--the spindle clamps being essential to support the drive spindles during intermediate roll change. The invention includes means to overcome this problem.